;(function() {
  var extra = {}

  c3.chart.internal.fn.additionalConfig = {
    data_pairs: []
  }

  c3.chart.internal.fn.beforeInit = function(config) {
    var that = this

    // update internals only when chart type is "bubble"
    if (config.data.type !== 'bubble') {
      return
    }

    // Set extra to ba able to be used in other part
    this.extra = extra

    extra.getKey = function(x, y) {
      return x + '::' + y
    }

    this.config.data_type = 'scatter'

    this.config.axis_x_padding = 0
    this.config.axis_y_padding = 0
    this.config.axis_x_tick_centered = true
    this.config.axis_x_tick_format = function(d) {
      return extra.names[d]
    }
    this.config.axis_y_tick_format = function(d) {
      return extra.names[d]
    }

    if (!config.color || !config.color.pattern) {
      this.config.color_pattern = ['#1f77b4']
    }

    this.config.point_r = function(d) {
      var names = extra.names,
        values = extra.values,
        base_length = extra.base_length,
        x = names[d.x],
        y = d.id,
        key = extra.getKey(x, y),
        value = !values[key] ? 0 : values[key],
        max,
        max_r,
        max_area,
        a,
        area,
        r

      if (!base_length) {
        base_length = extra.base_length = d3.min([
          that.svg
            .select('.c3-axis.c3-axis-y path')
            .node()
            .getTotalLength(),
          that.svg
            .select('.c3-axis.c3-axis-x path')
            .node()
            .getTotalLength()
        ])
      }

      max = d3.max(
        Object.keys(values).map(function(key) {
          return values[key]
        })
      )
      max_r = base_length / (names.length * 2)
      max_area = max_r * max_r * Math.PI

      a = max_area / max

      area = value * a
      r = Math.sqrt(area / Math.PI)

      return r
    }
    this.config.point_sensitivity = 25
    this.config.point_focus_expand_enabled = false

    this.config.legend_show = false

    if (!config.tooltip || !config.tooltip.contents) {
      this.config.tooltip_contents = function(
        d,
        defaultTitleFormat,
        defaultValueFormat,
        color
      ) {
        var x = extra.names[d[0].x],
          y = d[0].name,
          v = extra.values[extra.getKey(x, y)],
          text

        text = "<table class='" + this.CLASS.tooltip + "'>"
        text += "<tr><th colspan='2'>" + x + '&nbsp;/&nbsp;' + y + '</th></tr>'
        text += "<tr><td class='value'>" + (!v ? 0 : v) + '</td></tr>'
        text += '</table>'

        return text
      }
    }

    // construct bubble chart data and setup config based on the values

    var xs = this.config.data_pairs.map(function(pair) {
        return pair.x
      }),
      ys = this.config.data_pairs.map(function(pair) {
        return pair.y
      })

    extra.names = d3
      .set(xs.concat(ys))
      .values()
      .sort()

    this.config.axis_y_tick_values = extra.names.map(function(name, i) {
      return i
    })

    var data_xs = {}
    extra.names.forEach(function(name) {
      data_xs[name] = name + '_x'
    })
    var data_columns_xs = Object.keys(data_xs).map(function(key) {
      return [data_xs[key]].concat(
        extra.names.map(function(name, i) {
          return i
        })
      )
    })
    var data_columns_values = extra.names.map(function(name, i) {
      return [name].concat(
        extra.names.map(function(name) {
          return i
        })
      )
    })
    this.config.data_xs = data_xs
    this.config.data_columns = data_columns_xs.concat(data_columns_values)

    var values = {}
    this.config.data_pairs.forEach(function(pair) {
      if (!pair.x || !pair.y) {
        throw 'x and y are required in data.'
      }
      values[extra.getKey(pair.x, pair.y)] = pair.value
    })
    extra.values = values

    this.config.axis_x_min = this.config.axis_y_min = -0.5
    this.config.axis_x_max = this.config.axis_y_max = extra.names.length - 0.5
  }
})(window)
